Landing mat

ABSTRACT

THIS INVENTION RELATES TO EXTRUDED METAL LANDING MATS HAVING DECK AND BASE PLATES SPACED BY MEANS OF PARALLEL RIBS WITH PRE-FORMED COMPLEMENTARY END CONNECTORS BEING WELDED TO OPPOSITE ENDS OF THE MAT. THE END OF THE MAT IS REINFORCED BY INSERTING INTO THE CHANNELS BETWEEN ADJACENT RIBS A HOLLOW PLUG HAVING AN END WALL COEXTENSIVE WITH END OF THE RIBS, THE END CONNECTED THEN BEING ELECTRON BEAM WELDED OVER ITS ENTIRE REAR FACE TO THE END WALL OF THE PLUG AND THE END OF THE RIBS, DECK, AND BASE PLATES.

INVIJN'IY )R.

LEO M HARVEY Arm/9N6) June 22 1971 June 22, 1971 HARVEY Re. 27,147

LANDING MAT Original Filed March a, 1968 4 Sheets-Sheet 3 FIG.9

FIGJO FIGJI 47 TOR/v5 Y VEY I Re. 27,147

June 22, 1971 -Sheet 4 INVJ'TNTUR. LE0 M HARVEY nited States Patent@lice Re. 27,147 Retissued June 22, 1971 27,147 LANDING MAT Leo MyerHarvey, Los Angeles, Calif., assignor to Harvey Aluminum (Incorporated),Torrance, Calif. Original No. 3,450,010, dated June 17, 1969, Ser. No.711,681, Mar. 8, 1968. Application for reissue Nov. 4, 1969, Ser. No.870,653

Int. Cl. E01c 5/00 US. C]. 9413 21 Claims Matter enclosed in heavybrackets appears in the original patent but forms no part of thisreissue specification; matter printed in italics indicates the additionsmade by reissue.

ABSTRACT OF THE DISCLOSURE This invention relates toextruded metallanding mats having deck and base plates spaced by means of parallelribs with pre-formed complementary end connectors being welded toopposite ends of the mat. The end of the mat is reinforced by insertinginto the channels between adjacent ribs a hollow plug having an end wallcoextensive with end of the ribs; the end connected then being electronbeam welded over its entire rear face to the end wall of the plug andthe end of the ribs, deck, and base plates.

In conventional detachable interlocking matting, preformed complementarymale and female connectors are welded across opposite ends of each matsection (see US. Patent No. 3,172,508). When landing aircraft touch downat or near the end of a plank and/or a landing occurs on a section ofmatting overlying soil sufiiciently unstable to support the load,greater elastic deformation can occur in the body of the mat than in themore rigid end connector with resulting Weld failure and damage to theplank. Even normal aircraft traffic over the end of a plank causingrepated transverse fiexure thereof results in splitting or peeling ofthe upper deck plate from the mat structure. To avoid a tire puncture orother mishap by aircraft landing on damaged matting, the runway must beinspected frequently and damaged mat sections either rewelded orentirely replaced.

To improve the strength and durability of matting, it has been proposedto reinforce the extruded mat body by inserting into the end of eachchannel therein a relatively short tubular element (see US. Patent No.3,319,543). This tubular element is welded to adjacent ribs, the deckand base plates are beveled, and the end connector is then welded to thebeveled end of the plank and exposed edges of the tubular element. Sincethese tubular elements serve only to reinforce the extruded body of themat without strengthening to any degree the bond holding the endconnector thereto, repeated impact loading at the end of thesereinforced planks still results in rupture of the weld and separation ofthe end connector from the plank.

It is therefore a principal object of the invention to provide animproved and more durable matting assembled from a plurality of matsections each capable of sustaining repeated impact loading withoutfailure;

Another object is to provide an improved means of reinforcing both theend of the mat body and the Weld securing an end connector thereto;

Yet another object is to provide an improved end connector havingintegrally formed thereon a means of reinforcing the end of the matbody;

Still another object is to provide an improved process of welding an endconnector to a reinforced mat section.

These and other objects and advantages of the invention will becomeapparent upon reference to the following description, drawings, andclaims appended hereto.

According to a preferred embodiment of the invention, the end of the matis reinforced by slidably inserting into the channels a relatively shorthollow plug means having an end wall which closes off at least a portionof the channel. The rectangular plug means having peripheral wallsconforming closely in cross-section to that of the channels isdimensioned to fit slidably therein. Satisfactory reinforcement of themat is obtained with such plug tmeans having a length at least equal tothe over-all mat thickness, it being preferred to employ plugs having alength of from about 1.25 to 2 times the over-all mat thickness.

After positioning within the channels the plug means with their end wallcoextensive with the end of the plank, an end connector is weldedthereto. Although conventional welding techniques can be used insecuring the end connector to the mat body, it is preferred to employ anelectron beam welder, the electron beam being passed transverselythrough the mat to produce a continuous weld between the end connector,the ends of the extruded mat body, and the end wall of the plug means.

Mat sections fabricated according to the present invention havesurprisingly been found to withstand severe impact loading without afailure in either the body portion of the mat or in the weld securingthe end connector thereto. In the case of mat sections welded with anelectron beam, where the weld shear area is 3 to 4 times greater than inconventional matting, the fatigue life of the matting is unexpectedlyincreased by as much as two to three hundred percent.

In another preferred embodiment of the invention, the end of the matbody is reinforced by a plurality of fingerlike projections extendingfrom the back of the end connector means into the mat channels. Formaximum reinforcement, a pair of spaced parallel projections extend intoeach of the mat channels, one of the pair of projections being insliding contact with the underside of the deck plate and the otherprojection being in sliding contact with the upper surface of the baseplate. These finger-like projections which are formed integral with theextruded end connector means extend into the channels a distance atleast equal to the over-all mat thickness, and preferably a distance offrom about 1.25 to 2 times the over-all mat thickness.

With these finger-like projections of the end connector means being usedfor reinforcement of the mat body, conventional welding techniques canbe used in securing the deck and base plates to the end connector means.Even more satisfactory results can be obtained by using an electron beamto weld the end connector means to the mat body, the electron beamproducing an increased weld area by fusin gthe end of the ribs to theend connector means.

The invention will be more fully understood from the following detaileddescription of preferred embodiments illustrated in the drawings, inwhich:

FIG. 1 is a fragmentary perspective view, showing an end of a matsection with the hollow plug means used in reinforcing the mat channels;

FIG. 2 is a fragmentary perspective view, showing an end of a matsection with the plug means inserted into the channels;

FIG. 3 is a fragmentary perspective view, partly broken away, showing anend connector in welded position on the reinforced mat section;

FIG. 4 is a sectional view taken along lines 4-4 of FIG. 3, showing indashed lines the grooves in the back face of the end connector meansrelative to the perforations in the end wall of the plug means.

FIG. 5 is a sectional view taken along line 5-5 of FIG. 4, showing theend wall of the plug means welded to the end connector;

FIG. 6 is a sectional view taken along line 6-6 of FIG. 4, showing thegroove in the back face of the end connector means and the vent hole inthe end wall of the plug means.

FIG. 7 is a sectional view taken along line 77 of FIG. 5, showing theair passage through the end connector means;

FIG. 8 is a sectional view of the end of a mat section having an endconnector means with a pair of air passages formed therein;

FIGS. 9 and 10 are cross-sectional views through the end of a matsection showing the integral structure obtained by using an electronbeam to weld the end connector means to the mat body;

FIG. 11 is a fragmentary sectional view of the end of a mat sectionhaving attached thereto an improved end connector with a coupling barinserted therein;

FIGS. 12, 13 and 14 are perspective views of several plug means whichcan be used in reinforcing the channels in the mat;

FIG. 15 is a fragmentary perspective view of an extruded mat section andan end connector means having projections thereon which can be insertedinto the channels;

FIG. 16 is a fragmentary perspective view showing the end connector ofFIG. 15 welded to the mat body;

FIG. 17 is a sectional view taken along the stepped line 1717 of FIG.16, illustrating the manner in which the ribs extend into slots in theend connector;

FIG. 18 is a sectional view taken along line 1818 of FIG. 16;

FIG. 19 is a sectional view taken along line 1919 of FIG. 17.

Referring now to the drawings, a metal mat section having an extrudedbody portion indicated generally at 1 comprises a planar base plate 8, aspaced parallel deck plate 13 supported by a plurality of longitudinallyextending ribs 17 which are coextensive with the ends of the plates, andcomplimentary male and female side connectors 19, 21, respectively,formed on the opposite side edges of the body portion (FIGS. 1 and 2).The end of mat body 1 is reinforced by inserting hollow rectangularboxes or plug means 40 into the cells or channels 23 defined by adjacentribs and the deck and base plates.

The hollow plug means 40, illustrated in FIG. 1, has peripheral wallscomprising top and bottom walls 43, 45, respectively, and verticallyextending side walls 47, 49. Closing of one end of the plug means is anend wall 53 having a beveled surface 56 about hole or perforation 57therein. The cross-section of the plug means conforms closely to that ofchannel 23 to effect a tight fit of the plug therein, with the clearancefrom the walls of the channel being just sufficient to permit manualinsertion of the plug.

To effect the desired reinforcement of the ends of the mat, a hollowplug is employed whose peripheral walls are from about 0.5 to 1.5,morepreferably from about 0.75 to 1 as thick as rib 17, the thickness ofend wall 53 of the plug preferably being from about 1 to 2, morepreferably from about 1.25 to 1.75 as thick as the ribs. In a typicalmat section, for example, where the overall distance between the deckand base plate surfaces is about 1.25 inches and the rib thickness isabout 0.14 inch, the plug means employed has an overall length of about1.75 inches, a peripheral wall thickness of about 0.14 inch, and an endwall thickness of about 0.21 inch.

After the plug means are inserted into channels 23 with the end walls 53thereof coextensive with the end of ribs 17, the back face 60 of endconnector 63 is positioned in contact with the end of the mat section.The recess or groove 65 extending across the back face 60 of the endconnector communicates with apertures 57 in each of the plug means, thisgroove serving as an air passage between the side edge of the mat andeach of the channels 4 23 therein (FIGS. 3, 4, 6 and 7). In a preferredembodiment illustrated in FIG. 8, a pair of spaced parallel grooves 65and 65' in rear face 60 of the end connector both communicate with theaperture 57 in plug means 40.

The reinforced mat assembly with end connectors 63 secured thereto isthen placed in a vacuum chamber, the pressure in the chamber reduced toabout 100 microns, and a high desnity electron beam is passedtransversely through the mat along the juncture between the end connector and the body of the mat to produce weld 66 therebetween. Byutilizing an electron beam welder such as described in US. Patent Nos.3,187,216, 3,197,699, 3,- 274,425, and 3,365,091, the entire rear face60 of end connector 63 is fused to the walls 53, the end of ribs 17, andthe end of plates 8 and 13. It has been found that the beam of electronsgenerates sufficient heat during the welding operation to also fuse anedge of the peripheral walls of plug 40 to the interior of channel walls8, 13 and 17 (FIGS. 5, 9 and 10).

Suitable end connectors for use herein are preferably metal extrusionssuch as those shown in U.S. Patent No. 3,172,508. Although any of theconventional end connectors can be used with the reinforced matting ofthe present invention, it is preferred to employ an extruded endconnector 70 having a socket 73 into which is inserted a coupling bar75, a fuller description of this end connector being found in U.S.Patent No. 3,348,459 which is included herein by reference. The bodyportion of the mat as well as the end connectors and plug means can beextruded from any light metal. Suitable light metals are, for example,aluminum and the alloys thereof.

The end wall 53 of the plug means used in reinforcing the mat can haveone or more perforations therein to facilitate the venting of air fromchannels 23 during the electron beam welding. Suitable, for example, areplug means 40', FIG. 12, having a relatively large circular hole 57' inwalls 53, or plug means 40", FIG. 13, having a rectangular hole 57"milled in wall 53, or else, a plug means 40", FIG. 14, with two holes54, 55 in end wall 53. Under conditions of service where an electronbeam welded mat having a partial vacuum within the channels can betolerated, it is unnecessary to use a plug with a perforation in its endwall. With heavy duty mat, for example, any reduction in strength due toa partial vacuum in the channels is more than compensated for by theincreased strength of end wall 53 and the added weld area. If desired, asolid plug can be used to reinforce the end of the channels.

Although the supporting ribs are shown herein extending verticallybetween the deck and base plates, reinforcement of matting according tothe present invention can also be achieved where the ribs extend at anangle to these plates. It is only necessary that the cross-sectionalconfiguration of the plug means conform closely to that of the channel.

-By reinforcement of a mat body with the plug means of the presentinvention, and by using an electron beam in lwelding the end connectorto the mat, the weld area is at least doubled and in most cases tripled,depending upon the size of the aperture in the end wall 53. In a seriesof impact tests with reinforced matting of the present invention, it isfound that the fatigue life of the weld and the mat is increased by asmuch as three hundred percent. The matting of the present invention istherefore especially suitable in military applications where reliabilityis the price consideration since it may not always be possible toregularly inspect and repair mating in service.

In another preferred embodiment, reinforcement of the end of channels 23is achieved by utilizing an end connector means having a plurality ofspaced,'parallel upper and lower finger-like projections 83, 85,respectively, which can be inserted into channels 23 (FIGS. 15

to 19). When fully inserted into the channels 23, as shown in thecutaway section of FIG. 16, the upper projection 83 is in slidablecontact with and reinforces the under side of deck plate 13 betweenadjacent ribs 17, while lower projection 85 is in slidable contact withand reinforces base plate 8 intermediate the adjacent ribs.

A plurality of notches or grooves 86, FIGS. 15 and 17, separate eachpair of projections 83, 85, the ribs 17 preferably extending into thesegrooves beyond rear vertical face 84 of end connector 80. The grooves 86can be cut into extruded end connector 80 to any desired depth, it beingpreferred that these grooves extend a sufiicient depth into the endconnector so that face 84 thereof will lie a short distance withinchannel 23. To satisfactorily reinforce light weight matting, theprojections 83, 85 extend into the channels a distance at least equal tothe overall mat thickness. However, with medium or heavy duty matting,the desired reinforcement of the mat ends is obtained using finger-likeprojections which extend into the channels only a fraction of theover-all mat thickness.

To facilitate evacuation of channels 23 when welding with an electronbeam under a high vacuum, a notch or groove 88 which forms an air ventis cut in the end of each rib as well as in the outer wall of the maleside connector 19. When the pressure in the vacuum chamber is reduced toabout 100 microns at the outset of the welding operation, air in thechannels 23 flows out through grooves 88. After end connector 80 issecured to the mat by weld 90, air at atmospheric pressure is admittedinto the channels through the same grooves. In most cases, it ispreferred to then weld close the external groove in the side connector19 to prohibit entry of water or other debris into the body of the mat.

From the foregoing description, one skilled in the art can easilyascertain the essential characteristics of this invention, and withoutdeparting from the spirit and the scope thereof, can make variouschanges and modifications of the invention to adapt it to various usagesand conditions. Consequently, such changes and modifications areproperly, equitably, and intended to be, with the full range ofequivalence of the following claims.

What I claim is:

1. A reinforced mat section comprising an extruded body portion havingdeck and base plates spaced apart by a plurality of spaced ribs extendedbetween ends of said section and forming a plurality of cells,complementary side connectors formed integral with the body portion,hollow plug means fitting into ends of each of said cells with each ofsaid plugs having an outer end wall, and end connector means extendingacross and being welded to the end of said cells and to the end wall ofsaid plug means, whereby the outer end of said plug means becomes weldedto the end of said cells and to the end connector means during thewelding process.

2. The mat section as defined by claim 1, wherein a perforation in theend wall of the plug means communicates with a groove in the endconnector means, said groove extending across the end connector means toan end thereof, thereby forming an air passage for venting of the cells.

3. The mat section as defined by claim 1, wherein the plug means isrectangular in cross-section and extends into the cell a distance atleast equal to the over-all mat thickness.

4. The mat section as defined by claim 1, wherein the distance the plugmeans extends into the channel is from about 1.25 to 2 times as great asthe over-all mat thickness.

5. The mat section as defined by claim 1, wherein the body portion isextruded from a light metal selected from the group consisting ofaluminum and the alloys thereof.

6. A reinforced mat section comprising: an extruded body portion, and anend connected means secured to the end of the body portion, said bodyportion having deck and base plates spaced apart by a plurality ofparallel ribs extending longitudinally between the ends of the plateswith hollow cells being defined by said ribs and plates, said endconnector means having a plurality of integrally formed top and bottomfingers, said fingers being inserted into each of said cells, and theend of said cells being welded to the end connector means.

7. The mat section as defined by claim 6, wherein a pair top and bottomfinger extend into each of the cells, with the top finger being insliding contact with the deck plate and the bottom finger in slidingcontact with the base plate.

8. The mat section as defined by claim 6, wherein the fingers extendinto the cell a distance at least equal to the over-all mat thickness.

9. The mat section as defined by claim 8, wherein the distance thefingers extend into the cell is from about 1.25 to 2 times as great asthe over-all mat thickness.

10. The mat section as defined by claim 6, wherein the ends of the ribshave a groove therein which forms a passage between the inner wall ofthe end connectors and the ribs thereby, to facilitate venting of airfrom the cells.

11. The mat section as defined by claim 6, wherein the body portion isextruded from a light metal selected from the group consisting ofaluminum and the alloys thereof.

12. A reinforced mat section comprising an extruded body portion havingdeck and base plates spaced apart by a plurality of ribs extendinglongitudinally between the ends of said plates with hollow cells beingdefined by said ribs and plates; an end connector means rigidly joinedto an end of said deck and base plates and said ribs along the lengththereof; and strengthening means positioned in each of said hollow cellsbetween said ribs for strengthening said ribs with respect to buckling,one entire end of each of said strengthening means being permanentlyrigidly joined directly to said end connector means.

13. The mat section as defined by claim 12 wherein said body portion isextruded from a light metal 'selected from the group consisting ofaluminum and the alloys thereof.

14. The mat section as defined by claim 12 wherein said end connectormeans is of a solid one-piece construction and is provided with a socketinto which a coupling bar can be inserted in keying engagement.

15. The mat section as defined by claim 12 wherein said strengtheningmeans are integral projections from said connector means.

16. The mat section as defined by claim 12 wherein said end of said ribsis welded to said end connector means.

17. The mat section as defined by claim 16 wherein said strengtheningmeans is welded to said end connector means.

18. The mat section as defined by claim 17 wherein said deck plate andsaid base plate are welded to said end connector means along theirlateral end in the same plane as the weld joint joining saidstrengthening means to said end connector means.

19. The mat section as defined by claim 18 wherein said deck plate, saidbase plate, said ribs and said strengthening means are joined togetherby a single continuous weld joint.

20. The mat section as defined by claim 18 wherein said end connectormeans is of a solid one-piece construction and closes the ends of saidhollow cells, and is attached to said body portion and saidstrengthening means by a single continuous weld connection between saiddeck and base plates, said ribs, said strengthening means and said endconnector means which separately seals each of the hollow cells incooperation with said weld connection.

21. The mat section as defined by claim 18 having end connector means atboth ends thereof, one being male and the other female, each of said endconnector means having an irregular front wall surface which includes ahorizontally disposed recess open at one side and locked about midwaybetween the upper and lower surfaces of said end connector means, thefront wall of said male end connector means having a first dependingflange located above and forward of its said recess and a seconddepending flange'located below and rearward of said first flange, thefront wall of said female connector having a first overwide groove openupwardly and located above and somewhat rearward of its said recess forreceiving said first flange of a male end connector of an adjoining unitand having a second overwide groove open upwardly and located below andforward of its recess for receiving said second flange of said male endconnector means of the adjoining unit, the open sided recesses of saidmale and female end connectors when adjoining units are inter- 8 lockedforming a substantially closed slot for receiving a locking bar.

References Cited The following references, cited by the Examiner, are

5 of record in the patented file of this patent or the original JACOB L.NACKENOFF, Primary Examiner

